The long range goal of this research is to elucidate the role of brainstem structures in behavioral and autonomic temperature regulation in the primate Saimiri sciureus (squirrel monkey). Our method will comprise local thermal stimulation of certain CNS sites in the brainstem, spinal cord, and cortex, both individually and together, and the measurement of changes in the operant behavior that controls the temperature of the environment (skin) and/or the same local CNS sites. Simultaneous measurements will be made of metabolic, vasomotor, and sudomotor activity to determine the interplay between autonomic and behavioral thermoregulatory responses. Neurophysiological and neuroanatomical evidence has guided us in our choice of brainstem sites for study. Temperature-sensitive single neurons have been shown to exist in the preoptic area, lateral and posterior hypothalamus, midbrain, medulla, spinal cord, cortex, and the deep viscera. Many limbic system structures, such as the amygdala, hippocampus, and globus pallidus are intimately linked to the thermosensitive brainstem nuclei via the medial forebrain bundle and other tracts. As yet, the participation of most of these areas in normal thermoregulation is unknown. Using the methods developed in this laboratory for quantifying the total thermoregulatory response of the animal, we will proceed among three main lines of inquiry: 1) determine the CNS sites (e.g., spinal cord, medulla, globus pallidus, amygdala) that may, when heated or cooled, alter thermoregulatory behavior; 2) determine the characteristics of the behavioral control of local tissue temperature (e.g., brainstem, spinal cord, deep body, and restricted skin areas; and 3) assess the modification of behavioral and autonomic thermoregulatory responses that occurs during febrile states.